Cell Reports (Nov 2019)

Targeting Excessive EZH1 and EZH2 Activities for Abnormal Histone Methylation and Transcription Network in Malignant Lymphomas

  • Makoto Yamagishi,
  • Makoto Hori,
  • Dai Fujikawa,
  • Takeo Ohsugi,
  • Daisuke Honma,
  • Nobuaki Adachi,
  • Harutaka Katano,
  • Tsunekazu Hishima,
  • Seiichiro Kobayashi,
  • Kazumi Nakano,
  • Makoto Nakashima,
  • Masako Iwanaga,
  • Atae Utsunomiya,
  • Yuetsu Tanaka,
  • Seiji Okada,
  • Kunihiro Tsukasaki,
  • Kensei Tobinai,
  • Kazushi Araki,
  • Toshiki Watanabe,
  • Kaoru Uchimaru

Journal volume & issue
Vol. 29, no. 8
pp. 2321 – 2337.e7

Abstract

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Summary: Although global H3K27me3 reprogramming is a hallmark of cancer, no effective therapeutic strategy for H3K27me3-high malignancies harboring EZH2WT/WT has yet been established. We explore epigenome and transcriptome in EZH2WT/WT and EZH2WT/Mu aggressive lymphomas and show that mutual interference and compensatory function of co-expressed EZH1 and EZH2 rearrange their own genome-wide distribution, thereby establishing restricted chromatin and gene expression signatures. Direct comparison of leading compounds introduces potency and a mechanism of action of the EZH1/2 dual inhibitor (valemetostat). The synthetic lethality is observed in all lymphoma models and primary adult T cell leukemia-lymphoma (ATL) cells. Opposing actions of EZH1/2-polycomb and SWI/SNF complexes are required for facultative heterochromatin formation. Inactivation of chromatin-associated genes (ARID1A, SMARCA4/BRG1, SMARCB1/SNF5, KDM6A/UTX, BAP1, KMT2D/MLL2) and oncovirus infection (HTLV-1, EBV) trigger EZH1/2 perturbation and H3K27me3 deposition. Our study provides the mechanism-based rationale for chemical dual targeting of EZH1/2 in cancer epigenome. : A mechanism-based, effective strategy for controlling oncogenic H3K27me3 remains an open question. Yamagishi et al. provide the scientific rationale for dual targeting of EZH1+EZH2 in malignancies overexpressing EZH2, such as ATL, PTCL, and DLBCL, or harboring mutations in histone-modifying genes, as well as in pre-cancerous cells epigenomically perturbed by oncovirus infection. Keywords: EZH1, EZH2, H3K27me3, epigenetic drug, malignant lymphoma, adult T cell leukemia-lymphoma (ATL), HTLV-1, polycomb